What to Know About Meconium, Your Baby's First Poop

Baby's first poop is one of the first milestones your little one will hit — maybe even before coming out of the womb. The official name for this bowel movement is called meconium and fair warning: it can be a little startling.

Meconium "looks nothing like 'normal' poop," says labor, delivery, and postpartum expert, Lo Mansfield, RN. It's sticky, or as Mansfield calls it, "tarry," thick, and very dark in color.

It "usually happens after delivery, but can happen before delivery in an estimated 5 to 15 percent of cases," says Alison Cowan, MD, practicing ob-yn and head of medical affairs and Mirvie, a company developing predictive testing for life-threatening pregnancy complications.

"Babies typically will pass meconium on their own without an issue, and your pediatrician will check on this while you're still in the hospital," Dr. Cowan says. But for babies that pass meconium before birth, there can be an increased risk of breathing problems, specifically meconium aspiration (more on that later). It's also important to note that if your baby passes meconium in the womb, you might find that their skin and amniotic fluid is stained.

POPSUGAR spoke with two experts to help you better understand everything there is to know about meconium poop, meconium staining, meconium aspiration, and more. By the end of this article, you'll know everything you need to know about baby's first poop.

"Meconium is the first poop(s) that baby's body makes," says Mansfield. They start producing it as early as the end of the first trimester, she explains — typically from the things they ingest during pregnancy, like skin cells, amniotic fluid, and lanugo (fine hair that covers the fetus while growing).

The color of meconium depends on when your baby has the bowel movement. If it happens before birth, then the amniotic fluid can appear very dark brown or greenish, says Dr. Cowan. If your water breaks at home, your doctor or midwife will typically ask you whether the fluid is clear, green, or brown to assess whether the baby might have passed meconium, she says. They will also typically examine the fluid as part of your initial exam to assess whether this is the case.

"When babies pass meconium after birth, it appears black and is often described as 'sticky' and 'tarry,'" Dr. Cowan says. Meconium passed after birth can happen for some babies within the first few hours. For others, it may happen a day or two after delivery. The first few poops they have will all be meconium-type poops, per Mansfield. "As your baby starts eating and processing milk, the quality of the baby's stools will change over the first few days after birth, usually becoming the normal yellow 'seedy' newborn poop," Dr. Cowan says.

Meconium staining is essentially when "the amniotic fluid is actually 'stained' a different color because baby pooped inside," Mansfield says. How deep the staining is will vary based on how much meconium was passed and how long ago the stool happened. The fluid can range from a lighter yellowish/brown color to a deeper, thicker green or brown. "If babies have been sitting in that meconium-stained fluid for a while, it can even temporarily stain their skin," Mansfield explains. While not harmful in itself, meconium staining is a sign for healthcare providers to monitor for meconium aspiration.

There is an increased risk of meconium staining later in pregnancy (after 39 weeks), says Dr. Cowan — in addition to other complications, such as developing high blood pressure or preeclampsia in pregnancy, having a larger baby (this is called macrosomia), and even stillbirth. For this reason, doctors will recommend delivery if labor does not occur naturally within 1-2 weeks after your due date, Dr. Cowan says. "We also often recommend additional monitoring for pregnancies after the due date for this reason, particularly after 41 weeks.

Meconium aspiration is "when babies breathe in meconium-stained amniotic fluid before or during birth," Dr. Cowan says. Meconium aspiration syndrome is rare, occurring in 5 to 10 percent of births, per Johns Hopkins Medicine, but can cause severe illness and death in some newborns. The thick and sticky texture of meconium is what makes it so dangerous. "It can get stuck inside your baby's airways, prevent their lungs from inflating and deprive them of air," Cleveland Clinic states.

Some of the most common signs that your baby has aspirated meconium, per Cleveland Clinic, are:

Meconium aspiration can lead to significant breathing problems that require extra oxygen support, deep suctioning of the airways, and sometimes a temporary breathing tube, per Dr. Cowan. If your water breaks at home and it's green or brown, she recommends patients come to labor and delivery ASAP for an evaluation. If you've had meconium in your amniotic fluid, "there will usually be an extra nursery RN at your delivery so they can be there to assist if baby shows any signs of meconium aspiration," Mansfield says. "However, it's important to remember that these outcomes are rare, and that most babies with meconium in the [amniotic] fluid are healthy," Dr. Cowan explains.